PIN AS 4344385 - Caterpillar

Pressurized system: Hot coolant can cause serious burn. To open cap, stop engine, wait until radiator is cool. Then loosen cap slowly to relieve the pressure.
Failure to replace the engine's thermostat on a regularly scheduled basis could cause severe engine damage.
Caterpillar engines incorporate a shunt design cooling system and require operating the engine with a thermostat installed.If the thermostat is installed wrong, it will cause the engine to overheat. Inspect gaskets before assembly and replace if worn or damaged.
Illustration 1 g00890574
Replace the water temperature regulator in order to reduce the chance of problems with the cooling system. The water temperature regulator is located on the left side of the machine near the alternator.Replace the water temperature regulator and replace the seals while the cooling system is completely drained or while the coolant is drained to a level that is below the water temperature regulator housing.Note: If you are only replacing the water temperature regulator, drain the coolant to a level that is below the water temperature regulator housing.Reference: Refer to Disassembly and Assembly, SENR3611, "3126 Engines for Caterpillar Built Machines" for the correct procedure for replacing the water temperature regulator.